Expansion-valve.



EXPANSION VALVE. APPLICATION FILED nic. 21. 1910.

,11,z62231 111151110211 Apr. 16, 1918.

QQ w l v UNITED STATES PATENT OFFICE.

JOSIAH L. MERRILL, OF PITTSBURH, PENNSYLVANIA, ASSIGNOR T THE GENERALREFRIGERATION COV., A. CORPORATION OF OHIO.

EXPANSION -VALVE Specification of Letters Patent. @Patented Apr., 16,1918.

Application filed December 21, 1910. Serial No. 598,544.

A the following being a full, c ear, and exact disclosure of the oneform of in invention which I at present deem prefera le.

For a detailed description of the present forni of my invention,reference may be had `to the following specification and the .ac-

coinpanying drawing, which shows my screw of the adjusting needle (l.

valve partly in section.

Mv invention relates to valves employed to allow the passage, from acompression chamber into a space of lower pressure, of a gas such asanhydrous ammonia or other gas employed7 for example, in refrigeratiiigapparatus.

The usual practice in such valves has been to forni the small openingthrough which the gas flows in a disk of comparativel thin metal, theresult being that it is di tieult to expand the gas down to a very lowpressure, because on the outlet side there is formed in the disk a zoneor circle of chilled metal surrounding theopcning but at a slight radialdistance from the openin itself. This zone of chilled metal cuts o thetransmission of heat through the metal of the disk to the edges of theopening and the opening becomes wholly 'or partly closed by frost andice in the course of any long continued operation. lt is my intent torovide a valve for the expansion of sma ler amounts of material than hasheretofore been possible in continuous operation. To that end I form thevalve opening as a duct of considerable length through metalgof athickness, measured along the duct greater than the penetrating'eifectof the chi l produced by the expanding gas on the outlet side of theduct. Moreover, I give this duct a, gradually in'creasin therefrigerat-ing effect along the length of the duc'.. This also serves toconvert the pressure of the gas into velocity on the principle of theexpanding nozzle Y in a steam turbine. This tends to .produce a blast.which will dissipate any particles of ice or frost that tend to formand prevent their accumulation in or around the extremity of the duct.There is also a Smooth area from its inner Y to its outer end.. Bv t iismeans I distribute and gradually enlarging passageway from the Aorificeoutward which tendsto prevent -local eddies in the outward flow of thestream such as might result if 'the space were of pocket forni, or hadsubsequent restrictions or internally projecting shoulders. Such eddieswould tend to concentrate the chilling effect on the walls near to theneedle aperture.

Referring to the drawing, A represents the body of my valve. B is aninterior bushing seated against a shoulder in the bore of the valve andforming a nut for the Back of the bushingr is a washer I) and back ofthe washer is the space for the usual packing,

held in place by nut E. The gas enters the val ve by a passano G. f

At the'extrennty of body A. isa projection F in which is formed theescape opening for the gas in the forni of a. duct ll passing throughthe projection F and flared or enlarged toward its outlet end. Throughthis duct'H the high-pressure gas vin the body of the valve is allowedto escape into the low pressure space outside. The expansion of the gaswill`begin at the entrance to` the duct and will continue as it passes.through the duct in proportion to the enlargement in its' cross area.

This will distribute the chillin or refrigerating effect of theexpansion a ong the entire length of the duct and prevent itsconcentration at a particular point. vAt the saine time the mass ofmetal around the duct is of s uch length that the external chill aroundthe openimg' will not penetrate back along the duct far enough to eiltoff the conductivity of the metal around the throat of the duct.

From this it will be seen that the ressure on the iuld entering thepassage is converted into velocity as said fluid passes through'the duetH, the velocity of the gases carrying the frosting point well beyond thevalve. It will be noted that the taper of the duct H is so proportionedto the length of the duct that the maximum expansion of the fluid visobtained at ,tlieirear extremity thereof.

What claim as, new and desire to secure by Letters Patent is:

1. An expansion valve for refrigeratiiig systems comprising ay bodyhaving an inlet passage and an outlet duct communicating with saidpassage through a minute orifice,

the size of which is definitely proportioned to the size of the inletpassage to maintain pressure in the latter, said outlet duct beingelongated and flaring from said orifice "whereby the frost-ing point iscarried beyond the valve by the velocity of the refrigerating gas, thethickness of the metal, measuring along theductz being greater than thepenetrating e'ect of the chil-l produced by thev edjdying` back of theexpanding gas on the outlet side of the duct against the surroundingmetal, and a valve controlling said orilice.

2. An expansion lvalve for refrigerating systems comprising a bodyhaving an inlet passage and an outlet duct communicating with saidpassage through a minute orifice, the size of which is deinitelyproportioned tothe size vofathe inlet passage to maintain pressure inthelatter,

said body being provided with an extension through which the outlet ductextends longitudinally, the outlet duct being elongated and lHaring fromsaid oriiice, whereby the frosting point is carried beyond the valve bythe velocity of the refrigerating gas, the thickness of the metal,measuring along the duct, being greater than the penetrating effect ofthe chill produced by the eddying back of the expanding gas .on theoutlet side of the duct against the surrounding irnetal7 and a Valvecontrolling said orifice.

in witness whereof l have hereunto set my hand, before two subscribingwitnesses, this 12th day of December, 1910.

JOSlAl-I L. MERRILL.

Witnesses: Y

D. E. MITCHELL, llt. E. (irmvns.v

